Hitler didn't serve his full 5 year term. He was arrested a few days after the putsch of November 1923, went on trial in March and was sentenced April 1. He was a model prisoner and was released just nine months later on December 1, 1924. In total he only served 13 months in prison. He wrote Mein Kampf in that much shorter time period which may be why it's such a rambling work. Well, that and the fact that he was a madman. Good article.